Polyamide based mixed resin film roll and process for producing the same

Abstract

The problem to be solved by the present invention is to provide a biaxially oriented polyamide based mixed resin film roll with which bag forming processing by lamination is able to be performed smoothly and with high yield ratio and at the same time with which packages free of S-shaped curls can be obtained efficiently. A solution for the problem concerns the polyamide based mixed resin film roll of the present invention which includes a first sample cutout portion within 2 m from the winding end of film and a final cutout portion within 2 m from the winding start of film, and when a sample cutout portion is set up in approximately every 100 m from the first sample cutout portion, in all samples cut out from each of the cutout portions, physical properties such as elastomer content, elastic modulus in tension, boiling water shrinkage percentage and refraction index in the thickness direction are adjusted to be within a predetermined range of variation range.

1. A film roll wound up of a polyamide based mixed resin film composed of a mixed resin consisting of polyamide based resin and thermoplastic elastomer in a width of 0.2 m or more, 3.0 m or less, and a length of 300 m or more, 30000 m or less,
 wherein when a first sample cutout portion is set up within 2 m from the winding end of film and a final cutout portion is set up within 2 m from the winding start of film, and wherein when a sample cutout portion is set up in approximately every 100 m from the first sample cutout portion, the following requirements (1) and (2) are satisfied: 
 (1) when the content of thermoplastic elastomer constituent is measured for each sample cut out from each of the cutout portions, and the average content rate which is the average value of these content rates is computed, the degree of variability of the content of thermoplastic elastomer constituent of all the samples is within the ±10% range with respect to the average content rate, and 
 (2) the degree of variability of thickness throughout the full length in the longitudinal direction of a wound-up roll is within the range of ±2% to ±10% with respect to the average thickness; 
 wherein the thermoplastic elastomer of the polyamide based mixed resin film wound up is selected from polyamide based elastomers of block or random copolymers of polyamide based resin and polytetramethylene glycol or polyethylene glycol; and 
 wherein the amount of the thermoplastic elastomer of the polyamide based mixed resin film wound up is 1% by weight or more and 6% by weight or less. 
 
     
     
       2. The polyamide based mixed resin film roll according to  claim 1 , wherein when the elastic modulus in tension in the film winding-up direction is measured for each sample cut out from each of the cutout portions, the average elastic modulus in tension which is the average value of elastic moduli of the samples, is 1.30 GPa or more and less than 2.50 GPa and at the same time the degrees of variability of all samples are included in the range of ±10% with respect to the average elastic modulus in tension. 
     
     
       3. The polyamide based mixed resin film roll according to  claim 1 , wherein the number of pinholes when a 3000-cycle bending test is continuously carried out on each sample cut out from each cutout portion at the speed of 40 cycles per minute using a Gelvo type Flex-Cracking Tester is 10 or less in all cases. 
     
     
       4. The polyamide based mixed resin film roll according to  claim 1 , the roll wherein when a maximum boiling water shrinkage percentage of each sample cut out from each of the cutout portions is measured, the maximum boiling water shrinkage percentage being the maximum value of boiling water shrinkage percentages in all directions, an average boiling water shrinkage percentage which is average of the maximum boiling water shrinkage percentages is 3% to 6%, and a degree of variability in the maximum boiling water shrinkage percentages of all samples is within ±2% to ±10% relative to the average boiling water shrinkage percentage. 
     
     
       5. The polyamide based mixed resin film roll according to  claim 1 , the roll wherein when a directional difference of boiling water shrinkage percentage of each sample cut out from each of the cutout portions is measured, the directional difference of boiling water shrinkage percentage being the difference between a boiling water shrinkage percentage in the direction of +45° to the longitudinal direction and a boiling water shrinkage percentage in the direction of −45° to the longitudinal direction in an absolute value, an average directional difference of boiling water shrinkage percentage which is the average of the directional differences of boiling water shrinkage percentage is 1.5% or less, and a degree of variability in the directional differences of boiling water shrinkage percentage of all samples is within ±2% to ±10% relative to the average directional difference of boiling water shrinkage percentage. 
     
     
       6. The polyamide based mixed resin film roll according to  claim 1 , the roll wherein when refraction index in the thick direction of each sample cut out from each of the cutout portions is measured, an average refraction index which is the average of the refraction indexes is 1.500 or more, 1.520 or less, and a degree of variability in the refraction indexes of all samples is within ±2% relative to the average refraction index. 
     
     
       7. The polyamide based mixed resin film roll according to  claim 1 , the roll wherein the major component of polyamide composing the polyamide based mixed resin film is nylon 6. 
     
     
       8. The polyamide based mixed resin film roll according to  claim 1 , the roll wherein the major component of thermoplastic elastomer composing the polyamide based mixed resin film is at least one kind of polyamide-based elastomer and polyolefin-based elastomer. 
     
     
       9. The polyamide based mixed resin film roll according to  claim 1 , the roll wherein the polyamide based mixed resin film wound up is laminated with a polyolefin based resin film. 
     
     
       10. The polyamide based mixed resin film roll according to  claim 1 , the roll which is a polyamide based mixed resin film wound up wherein an unoriented sheet-like material obtained by extruding molten polyamide based resin from a T-die and cooling by contact with a metal roll is biaxially stretched. 
     
     
       11. The polyamide based mixed resin film roll according to  claim 1 , the roll which is a polyamide based mixed resin film wound up being stretched by a tenter stretching method. 
     
     
       12. The polyamide based mixed resin film roll according to  claim 1 , the roll which is a polyamide based mixed resin film wound up being sequentially biaxially stretched. 
     
     
       13. The polyamide based mixed resin film roll according to  claim 1 , the roll which is a polyamide based mixed resin film wound up being biaxially stretched in the longitudinal direction and the transverse direction. 
     
     
       14. The polyamide based mixed resin film roll according to  claim 1 , the roll which is a polyamide based mixed resin film wound up wherein an essentially unoriented sheet-like material of polyamide based resin is stretched in at least two stages in the longitudinal direction in threefold or more at a higher temperature than the glass transition temperature of the main component of the polyamide based resin plus 20° C., then stretched in the transverse direction in threefold or more. 
     
     
       15. The polyamide based mixed resin film roll according to  claim 1 , the roll which is a polyamide based mixed resin film wound up being thermally fixed after a final stretching treatment. 
     
     
       16. The polyamide based mixed resin film roll according to  claim 1 , the roll which is a polyamide based mixed resin film wound up being relaxed after thermal fixation. 
     
     
       17. The polyamide based mixed resin film roll according to  claim 1 , the roll wherein at least one kind selected from the group consisting of lubricant, anti-blocking agent, thermal stabilizer, antioxidant, antistatic agent, light resistant agent and impact modifier is added to the polyamide based mixed resin film wound up. 
     
     
       18. The polyamide based mixed resin film roll according to  claim 1 , the roll wherein inorganic particle is added to the polyamide based mixed resin film wound up. 
     
     
       19. The polyamide based mixed resin film roll according to  claim 1 , the roll wherein the inorganic particle is a silica particle of 0.5-5.0 μm in an average diameter. 
     
     
       20. The polyamide based mixed resin film roll according to  claim 1 , the roll wherein a higher fatty acid is added to the polyamide based mixed resin film wound up. 
     
     
       21. A production method of polyamide based mixed resin film roll according to  claim 1 , comprising: a step of film forming while melt-extruding polyamide based resin chip and thermoplastic elastomer chip; a step of biaxial stretching wherein an unstretched film obtained in the step of film forming is stretched biaxially in the longitudinal direction and the transverse direction; and a step of roll forming by winding up the biaxially stretched film, and satisfies the following requirements (1) and (2). 
       1) The step of film forming includes melt extrusion after polyamide based resin chip and thermoplastic elastomer chip are mixed, wherein the shape of each resin chip used is elliptic cylinder having elliptic cross section with a major axis and a minor axis, and the thermoplastic elastomer chip is adjusted each in its average major axis, average minor axis and average chip length so as to be within a range of ±20% relative to the average major axis, average minor axis and average chip length of the polyamide based resin chip. 
       2) The step of film forming includes melt extrusion after polyamide based resin chip and thermoplastic elastomer chip are mixed, wherein mixing of the polyamide based resin chip and thermoplastic elastomer chip is performed with a sublimation segregation inhibitor. 
     
     
       22. The production method of polyamide based mixed resin film roll according to  claim 21  wherein the step of biaxial stretching includes a stretching in the transverse direction after a stretching in the longitudinal direction in two stages and the stretching ratio in the first stage of two-stage stretching in the longitudinal direction in the step of biaxial stretching is higher than the stretching ratio in the second stage. 
     
     
       23. The production method of polyamide based mixed resin film roll according to  claim 21 , further comprising a step of melt extrusion using an extruder equipped with a funnel-shaped hopper as a feed section of material chip, wherein an angle of slope of the hopper is adjusted to 65° or more, a water content of polyamide based resin chip and thermoplastic elastomer chip before being fed to the hopper is adjusted to 800 ppm or more, and 1000 ppm or less, and furthermore a temperature of polyamide based resin chip and thermoplastic elastomer before being fed to the hopper is adjusted to 80° C. or more. 
     
     
       24. The production method of polyamide based mixed resin film roll according to  claim 21 , further comprising a step of preheating conducted before a step of longitudinal stretching and a step of thermal treatment conducted after the step of longitudinal stretching in the step of biaxial stretching, wherein a variation width of surface temperature of film at any point of the step of longitudinal stretching, 
       the step of preheating and the step of thermal treatment and the step of longitudinal stretching is adjusted over the entire film length within a range of ±1° C. to the average temperature. 
     
     
       25. The production method of polyamide based mixed resin film roll according to  claim 21 , wherein the step of film forming includes a roll cooling step of winding up melted resin extruded from an extruder on a cooling roll, wherein a part contacting the melted resin with the surface of cooling roll is sucked over the entire width of melted resin by a suction unit in the opposite direction to the winding up direction.